Theoretical and Applied Genetics

, Volume 101, Issue 1, pp 7–14

The contribution of short repeats of low sequence complexity to large conifer genomes

  • A. Schmidt
  • R. L. Doudrick
  • J. S. Heslop-Harrison
  • T. Schmidt
Original Paper

DOI: 10.1007/s001220051442

Cite this article as:
Schmidt, A., Doudrick, R., Heslop-Harrison, J. et al. Theor Appl Genet (2000) 101: 7. doi:10.1007/s001220051442
  • 124 Views

Abstract 

The abundance and genomic organization of six simple sequence repeats, consisting of di-, tri-, and tetranucleotide sequence motifs, and a minisatellite repeat have been analyzed in different gymnosperms by Southern hybridization. Within the gymnosperm genomes investigated, the abundance and genomic organization of micro- and minisatellite repeats largely follows taxonomic groupings. We found that only particular simple sequence repeat motifs are amplified in gymnosperm genomes, while others such as (CAC)5 and (GACA)4 are present in only low copy numbers. The variation in abundance of simple sequence motifs reflects a similar situation to that found in angiosperms. Species of the two- and three-needle pine section Pinus are relatively conserved and can be distinguished from Pinus strobus which belongs to the five-needle pine section Strobus. The hybridization pattern of Picea species, bald cypress and gingko were different from the patterns detected in the Pinus species. Furthermore, sequences with homology to the plant telomeric repeat (TTTAGGG)n have been analyzed in the same set of gymnosperms. Telomere-like repeats are highly amplified within two- and three- needle pine genomes, such as slash pine (Pinus elliottii Engelm. var. elliottii), compared to P. strobus,Picea species, bald cypress and gingko. P. elliottii var. elliottii was used as a representative species to investigate the chromosomal organization of telomere-like sequences by fluorescence in situ hybridization (FISH). The telomere-like sequences are not restricted to the ends of chromosomes; they form large intercalary and pericentric blocks showing that they are a repeated component of the slash pine genome.Conifers have genomes larger than 20000 Mbp, and our results clearly demonstrate that repeats of low sequence complexity, such to (CA)8, (GA)8, (GGAT)4 and (GATA)4, and minisatellite- and telomere-like sequences represent a large fraction of the repetitive DNA of these species. The striking differences in abundance and genome organization of the various repeat motifs suggest that these repetitive sequences evolved differently in the gymnosperm genomes investigated.

Key words PinusGymnospermsSimple sequence repeatsMicrosatellitesMinisatellitesTelomere

Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • A. Schmidt
    • 1
  • R. L. Doudrick
    • 2
  • J. S. Heslop-Harrison
    • 3
  • T. Schmidt
    • 1
  1. 1.Institute of Crop Science and Plant Breeding, Olshausenstraße 40, D-24118 Kiel, Germany e-mail: kamm@plantbreeding.uni-kiel.de Tel.: +49/431/8803288, Fax: +49/431/8802566DE
  2. 2.Southern Institute of Forest Genetics, Southern Research Station, USDA Forest Service, 23332 Highway 67, Saucier, MS 39574–9344, USAUS
  3. 3.Karyobiology Group, Department of Cell Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, U.K.GB